(1) Field of the Invention
The present invention relates to a data transfer apparatus, a data transfer method, and a program, for transferring data using direct memory access.
(2) Description of the Related Art
There are various technologies using the direct memory access DMA (hereinafter, referred to as DMA). One of the examples is disclosed in Japanese Patent Application Laid-Open No. 5-204833 as a DMA transfer controller which controls data transfer, using the DMA, between each of multiple peripheral devices and a memory. This DMA transfer controller has multiple channels, each of which is allocated to each peripheral device. The peripheral devices are connected to the memory via a single bus. When there are conflicts in DMA requests issued from the multiple peripheral devices, the DMA transfer controller arbitrates for these DMA requests. More specifically, the multiple channels -are grouped, and the DMA transfer is executed in an order firstly from a DMA request belonging to a group having a higher priority. The DMA transfer for a DMA request belonging to a group having a lower priority is executed, when the DMA request belonging to the group having a higher priority does not exist. For the DMA requests included in each group, the DMA transfers are executed circularly.
Thereby, the DMA transfers are executed for the groups, in the order of priority. Moreover, for each group, only a specific channel is not used exclusively, but the multiple channels are used equally during the DMA transfers,